Ok since someone dug this up:
The reason why this is controversial is because every person finds different things hard. English is so different from maths, which is so different to something like bio, which is again a world apart from languages. Here's my take on my own subjects - I can really speak for the others.
Personally, as someone who does languages, I believe that basically all the languages (continuers+, not beginners) are pretty much harder than anything else unless you have some kind of background in them. Learning to understand, speak, read and write an entirely new language well would be absolutely gruelling (I'm fortunate to have some prior knowledge of my language, but I could not imagine doing it otherwise).
I do both bio and eco, and even though they're both super content-heavy, they're very different. Neither content is that hard to learn, but imo eco is typically more intuitive while bio is more compartmentalised (easier to classify/sort). The most annoying part about eco content is stat/policy memorisation. Eco MCQs are nothing compared to essays and the amount of prep that has to go into them (feeling that rn...). Bio papers are much more approachable as they're just MCQs and SAQs, but the hardest part is understanding and hitting all the marking criteria. You can know all the content from head to toe but score terrible marks if you don't write what the markers want to see, e.g. if you miss definitions, key words, incorporation of stimulus material/stats, etc., or if your scientific skills aren't up to par.
ENGLISH ON TOP - unless you're a very specific breed of student, English is always a challenge, albeit maybe a bit more mundane than languages because you can just memorise essays and practise adapting them.
I also agree that maths can be put lower. Maths adv is a breeze if you do enough homework and grind enough past papers. Maths ext 1 should still be high imo, but it's also about the practice.